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PGA302: PGA302 T ADC GAIN

Seok Kim1
Intellectual 280 points
Part Number: PGA302

Hello,

I use a magnet and Hall sensor connected to the PGA302.

We found that the magnet, Hall sensor and PGA302 are affected by temperature.

P ADC's GAIN is set to 40.
The T ADC is said to compensate for temperature.

I tested whether it compensates for 0°C, 25°C and 50°C by setting it to 3 Pressure, 3 Temperature in the PGA302 GUI.

But the result didn't go the way I wanted.

Internal Temp Sensor is set in T MUX with EEPROM.
I set the T ADC GAIN to 1.33.

Looking at the datasheet, there were calculations for -40°C, 0°C and 150°C.
When T GAIN is set to 4 at 10°C, the T ADC Value of 4340 was output from the Data Monitor.
Calculation according to the data sheet yielded -68°C.

1.(T ADC Code = 20 x Temp + 5700
(4340-5700)/20 = Temp
Temp = -68)
Is it correct to calculate like this?

2. If T ADC GAIN is set to 4, can it be calculated using the Decimal value displayed in the Data Monitor?

The temperature is adjusted using the Temperature& Humidity Chamber.

3. How do I set the T ADC part to output the T ADC Code according to the calculation formula for -40°C, 0°C, 150°C as shown in the data sheet?
Only need to set T GAIN = 4, Enable Internal Temp Sensor?

4. How do I set up if I want to use an external temperature sensor?

thanks.

  • 0
    TI__Mastermind 31655 points

    Hi Seok,

    Is TGAIN set to 1.33 or 4 V/V? In either case, the value of 4340 is definitely off if the device is at room temperature. I would expect something closer to 6000+ if the equations are correct. I will double check that the formulas for the temperature measurement are correct.

    Yes, the data monitor will show decimal values that you can enter into the temperature formulas, and a gain of 4 V/V should correspond to those formulas. Note that the internal temperature sensor also needs to be used in single-ended mode (configured in the T_GAIN_SELECT register). This could account for the error you are seeing, if you are currently using the internal sensor in differential mode.

    To use an external sensor you have to configure the TMUX setting to take the input from the VINTP/VINTN pins instead of the internal temperature sensor, and configure the input mode (single-ended or differential) based on the type of sensor you are using.


    Regards,